Patent GB-916969-A (GB)
Title: Improvements in or relating to friction type overrunning clutches and gear boxes incorporating such clutches.
IPC: F16H3/091
Filed: 1959-02-16
Abstract: 916,969. Ratchet clutches; friction clutches; change-speed gear. RAMBAUSEK, H. Feb. 16, 1959 [Feb. 14, 1958 (2)], No. 5364/59. Class 80 (2). A friction ratchet clutch comprises a driving shaft 1 carrying a sleeve 4<SP>1</SP> upon which are threaded two clutch hubs 7<SP>1</SP>, 7<SP>11</SP> biased to turn inwards upon the thread and engage a central abutment 36 by springs 11, 11<SP>1</SP>, the clutch hubs being splined to carry clutch discs 8 interleaved with clutch discs 17 splined within a driven hub 16 fast with an output gear 39 and a clutch control ring 32 sliding axially to act through a thrust bearing 30 so that a pressure sleeve 18, 19 engages the discs to transmit drive. The two clutch hubs 71 carry needle roller bearings 23 or like anti-friction means which engage the end discs of the clutch pack, divided into two parts by a central spacer 37. The clutch control ring 18, 19 is in two parts connected by bolts 20, the effective length of which can be adjusted to compensate for wear in the clutch. To engage the clutch, the control ring 32 is slidden, e.g., rightwards of Fig. 1, so that the pressure ring 18 compresses the packs of clutch discs 8, 17. Torque is then transmitted from the driving shaft 1 through the clutch packs to the driven clutch hub 16 and the output gear 39. If the output gear 39 tends to overrun the driving shaft 1, the associated clutch hub 7<SP>1</SP>, 7<SP>11</SP> is screwed along the threaded sleeve 4<SP>1</SP> against the bias of the springs 11 to the disengaged position, and over-running is permitted. When the output gear 39 tends to slow down relatively to the driving-shaft 1, the hubs 7<SP>1</SP> screw back to their original positions and the clutch reengages. To enable drive to be transmitted from the shaft 1 to the gear 39 in the opposite direction of rotation, the pressure ring 32, formerly slidden rightwards of Fig. 1, is instead slidden leftwards. To maintain the clutch engaged so that over-running cannot take place, the control ring 32 is slidden further rightwards (or leftwards) from the position causing normal engagement, so that the disengaging screwing motion of the clutch hubs 7<SP>1</SP> is neutralized. The control ring 32 is slidden axially by mechanical, hydraulic, pneumatic, electric or magnetic means, not further described. In a modification, Fig. 4 (not shown), the threaded sleeve 4<SP>1</SP> and the abutment 36 are each in two parts. Ratchet clutches according to the invention may be incorporated in constant-mesh changespeed countershaft gearing. In one form, a driving-shaft 1, Fig. 11, can be connected by a ratio establishing friction clutch K 1  to a gear 3 meshing a gear 5 fast upon a countershaft 4. A friction ratchet clutch U 1  according to the invention can be engaged to connect the countershaft 4 to a gear 7 meshing a gear 6 on a layshaft 10 which can be clutched to the driving- shaft 1 by a ratchet clutch œ 1 engageable to transmit rotation in one direction only. A similar frictional ratchet clutch œ 2 can be engaged to connect the countershaft 4 to a gear 8 meshing a gear 9 fast upon a driven shaft 2, the layshaft 10 and the driven shaft being clutched together when a ratio establishing friction clutch K 2  is engaged. The gearing gives four ratios, the numerical ratios obtained being in geometric progression. In one modification, Fig. 1A (not shown), a driving-shaft 1 drives through one or other of two alternatively engaged forward or reverse drive clutches to a simple countershaft gear giving two ratios. In another modification, Fig. 6 (not shown), a driving shaft carries alternatively engaged forward and reverse clutches meshing directly, and through an idler, with a double gear clutched by a friction ratchet clutch according to the invention to a parallel driven shaft. Similar modifications, Figs. 14, 19 (not shown) give three forward and three reverse ratios, and in another modification, Fig. 24 (not shown), three friction ratchet clutches according to the invention are used to obtain four forward and four reverse ratios. Further modifications are also described giving up to eight ratios.